There was uncertainty over whether the Soviets could sustain their advance on Germany, and rumours of the establishment of a Nazi redoubt in Southern Germany were taken too seriously. The Allies saw the Dresden operation as the justified bombing of a strategic target, which United States Air Force reports, declassified decades later, noted as a major rail transport and communication centre, housing factories and 50, workers supporting the German war effort.
In the decades since the war, large variations in the claimed death toll have led to controversy, though the numbers themselves are no longer a major point of contention among historians. Early in , the German offensive known as the Battle of the Bulge had been exhausted, as was the Luftwaffe 's failed New Year's Day attack. The German army was retreating on all fronts, but still resisting. Alternatively, the report warned that the Germans might hold out until November if they could prevent the Soviets from taking Silesia.
Despite the post-war assessment, there were serious doubts in Allied intelligence as to how well the war was going for them, with fears of a "Nazi redoubt " being established, or of the Russian advance faltering. A large scale aerial attack on Berlin and other eastern cities was examined under the code name Operation Thunderclap in mid, but was shelved on 16 August.
On 5 January , two North American B Mitchell bombers dropped , leaflets over Dresden with the "Appeal of 50 German generals to the German army and people". On 22 January , the RAF director of bomber operations, Air Commodore Sydney Bufton , sent Deputy Chief of the Air Staff Air Marshal Sir Norman Bottomley a minute suggesting that if Thunderclap was timed so that it appeared to be a coordinated air attack to aid the current Soviet offensive, then the effect of the bombing on German morale would be increased.
Marshal of the Royal Air Force Sir Charles Portal , the Chief of the Air Staff , answered: "We should use available effort in one big attack on Berlin and attacks on Dresden, Leipzig, and Chemnitz, or any other cities where a severe blitz will not only cause confusion in the evacuation from the East, but will also hamper the movement of troops from the West. Churchill was not satisfied with this answer and on 26 January pressed Sinclair for a plan of operations: "I asked [last night] whether Berlin, and no doubt other large cities in east Germany, should not now be considered especially attractive targets Pray, report to me tomorrow what is going to be done".
